The invention relates to a transmission for driving a swivel joint between two elements which are rotatable relative to each other.
Cycloid transmissions of the generic type, such as disclosed, for example, in German patent document DE-OS 34 18 686, are normally used for the rotational-speed gearing between two shafts, particularly if high gear ratios are required. In this case, a multiple eccentric is usually coupled to a drive shaft, and the driving element is coupled to an output shaft. For generating high rotational speeds, the driving shaft and the output shaft may also be interchanged. It is also possible to use such a transmission , in a simplified construction such as disclosed in German patent document DE-OS 34 07 245 for example, as a torque wrench, in which case a drive shaft and an output shaft are also necessary. A further example of a transmission of the type initially mentioned above is disclosed in German patent document DE-OS 32 06 992, in which for the support of the driving pins on both ends, driving disks are arranged at both sides of the cam disks (cycloid disks). and these two driving disks, at their outer circumference, are at the same time used for the (radial and axial) bearing of the "roller ring" central wheel, specifically with the insertion of separate bearings. In this case, the driving disks are stationary transmission parts, either with respect to a stationary frame (such as the vehicle frame) or with respect to a moving output shaft, the "roller ring" central wheel carrying out the function of either the output shaft or of the transmission "frame ring" central wheel carrying out the function of either the output shaft or of the transmission frame.
It is an object of the invention to provide a transmission of the generic type which is adapted to be used as a joint between components that can be swivelled relative to one another, this joint being operable by means of a single shaft.
This object is achieved according to the invention, by fixing the driving disks in a stationary position so that, when the multiple eccentric is rotated, the cam disks are driven by way of the driving pins, thus causing the central wheel to rotate. As an alternative, it is also possible in the case of a transmission according to the invention, to lock the central wheel instead of the driving disks so that, when the multiple eccentric is driven, the cam disks are driven by the central wheel thereby causing the driving disks to rotate. As a result, the transmission may be used as a swivel joint between a component fixedly connected with the central wheel and a component fixedly connected with the driving disks, in which case, when the multiple eccentric is driven by a shaft or the like, one (locking) component remains stationary, and the other component is swivelled by the central wheel or the driving disks depending on the assignment.
An advantage of the transmission according to the invention is that, a compact construction is ensured, in which neither the bearing devices nor the locking devices of the driving disks and of the central wheel require a lot of space. Thus, no separate bearing is required for the radial support of the central wheel. Consequently, this transmission is suitable for all applications of a swivel joint with a relatively low space requirement while the stability under load is high.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.